The invention relates to the field of plant propagation and more specifically to the mass propagation of plants with plant parasites, preferably of plants with green plant parasites, so called hemi-parasites.
This application claims the priority of Danish patent application no. PA 2001 01078 filed on Jul. 9, 2001, which is hereby incorporated by reference in its entirety. All patent and non-patent references cited in that application, or in the present application, are also hereby incorporated by reference in their entirety.
Plants with plant parasites are grown for a variety of purposes. Some plant parasites such as mistletoes contain active ingredients that are used as pharmaceutical preparations for treating a number of diseases including cancer and AIDS.
Mistletoe may also be used for producing medicaments for the treatment of diseases of the small intestine (disorders caused by medicaments or infections), of bone marrow (aplasia and insufficiency, for instance as a result of agranulositosis caused by medicaments or radiation), of the thymus (dysfunction, aplasia or hypoplasia), the spleen (dysfunction), lymph nodes (aplasia or hypoplasia resulting from disorders caused by medicaments or radiation), for adjuvant treatmentxe2x80x94also combined with chemopharmaceuticalsxe2x80x94of analgesia, of liver, pancreas and kidney disorders as well as malign tumors, specially of breast, cervical, colon or prostate carcinoma. Viscum dry extracts can also be used to stimulate cellular immunity, to treat leucocytopenia, granulocytopenia, lymphocytopenia, erythrocytopenia as well as immunoglobulin deficiencies as a result of cancer, disorders characterized by a deficiency of the immune system, specially AIDS, in addition to bacterial and viral induced symptoms such as inflammatory disorders of the small intestine, the pancreas and the kidneys, hepatitis A, B and C, skin lesions (ulcus cruis), herpes simplex I and II as well as herpes zoster, and also to treat hyperlipoproteinemia with high levels of cholesterol, LDL cholesterol, triglycerides and low levels of HDL cholesterol (WO 98/13053).
Plants with parasites, especially hemi-parasites, are also grown for ornamental purposes and are used as pot plants, bonzais or ornamental garden plants. Due to high production costs this market has been very limited up till now. However, world wide there is an increased demand for unusual plants, not just for plant collectors but also for ordinary consumers of pot plants. Mistletoes are traditionally associated with Christmas in a number of countries, and it is believed that price is the primary obstacle against pot plants with mistletoes becoming a major sales success during the Christmas season. A significant market for mistletoes is the sale as cut-green or cut-greens. Branches for this purpose are normally cut in nature in areas of massive mistletoe infections.
The commercial production of pot plants and ornamental garden plants is very limited due to high costs associated with the steps required to produce a plant with an established plant parasite. Traditionally, production is done in a two step process. In the first step the mother plant is propagated by any known means such as germination of seeds, by cuttings, by grafting or through in vitro culture and subsequently grown to a certain size. In the second step, the plant parasite is established on the host plant, and after successful establishment the plant is cultured until the plant parasite has reached an acceptable size. The period from sowing the seed on the host plant until the plant is ready for sale may well take two to three years or more. For a plant that is to be sold in a temperate climate zone, this production is normally carried out in greenhouses, since most pot plants are of tropic or sub-tropic origin. Due to the requirement for greenhouse facilities and the length of the production period, the prize of such a product is prohibitively high for the average consumer.
Growing the plants with the plant parasite outdoors under tropical or sub-tropical conditions may lower the costs for climate control, but shipping costs make this possibility less attractive. Besides, most countries or regions have restrictions against the import of rooted plants with soil, due to the risk of spreading plant pathogens.
Consequently, the price of such plants is very high and there is a need in the field to provide cost effective methods for producing plants with established plant parasites to be used as pot plants, ornamental plants and for production of plant parasite biomass for pharmaceutical purposes.
In a first aspect the invention relates to a method for preparation of a plant comprising in successive order establishing at least one plant parasite on at least one branch of a host plant, cutting at least one branch with at least one established plant parasite, and rooting the at least one cut branch.
Preferably, the invention relates to host plants for which commercially feasible methods for propagation via cuttings are available or can be developed.
In a number of investigated cases it turns out that the cuttings are capable of rooting with substantially the same rooting percentages as cuttings without plant parasites despite the presence of the parasites. This is unexpected due to the presence of the plant parasite.
Furthermore, several advantages are obtained by the inventive method.
Many plant parasites may be established on the same motherplant. Thereby less space is taken up by the method compared to prior art methods. Furthermore, large and strong mother plants can be used as hosts for the parasites. Large plants can more easily tolerate the presence of the parasites and can better support the growth of the parasites. After cutting the first series of cuttings from the motherplant, a new series of plant parasites can be sown on the branches of the same motherplant to produce a new round of cuttings with plant parasites.
Another great advantage is that the host plant with the parasites can be grown outdoors in a climate zone suitable for the host plant, preferably in its natural distribution area. Cuttings carrying the established plant parasite can then be shipped to the climate zone where the plants are to be sold ultimately. Cuttings can normally be imported without any quarantine restrictions. In the climate zone, where the plants are to be sold the cuttings can be rooted and grown until ready for sale. Thereby the time necessary in greenhouse can be considerably shortened.
According to another aspect, the invention relates to a method for preparation of a plant comprising in successive order
establishing at least one plant parasite on a first host plant,
cutting at least one piece of the first host plant with the at least one established plant parasite, and
grafting the at least one cut piece on a second host plant using tip-budding.
One advantage of this aspect of the invention is that the production time can be reduced. Preferably the plant parasites are established on relatively large and healthy host plants, on which the parasites can grow to a considerable size. As soon as the graft union is successful the plant is ready for sale.
According to a further aspect the invention relates to a rootable cutting of a host plant comprising at least one established plant parasite. Some of the advantages of the rootable cutting have been mentioned above. A rootable cutting with at least one plant parasite can easily and relatively rapidly be rooted and grown to a size suitable for sale.
When making the cutting, due care can be taken to the appearance of the finished garden- or pot plant product. For example, the cutting can be made so that the parasite is located in the lower or upper portion of the sales-plant. The parasite can be located on the main stem or on a side branch of the cutting. Furthermore, the cutting can be cut above the place of the plant parasite to produce a plant with more side branches. In other applications, it may be of interest to select a position for the plant parasite, which makes it easy to harvest the plant parasite either for biomass production or for production of cut-greens in plantations.
According to a further aspect the invention relates to a method for manufacturing a pharmaceutical composition comprising producing a plant according to the method disclosed above, growing the plants, harvesting plant parasite biomass, and producing a pharmaceutical composition from the plant parasite biomass.
By combining the inventive plant propagation method with growing of plant parasite biomass, the costs associated with this production can be lowered. When the plant parasites are established on the host plant and when the cuttings are cut, due care can be taken to the placement of the plant parasite on the plant to be grown in the field, so that the parasite is grown in a height, from which it is readily harvestable by hand or machine.
Definitions
Plant Parasite
Parasitic plants are here defined as vascular plants which have developed specialised organs for the penetration of the tissues of other vascular plants (hosts), and the establishment of connections to the vascular strands of the host to the end of absorption of nutrients by the parasite. These organs (albeit of different morphological nature in different parasitic plants) are termed haustoria. Most known parasitic plants thus defined belong to the dicotyledons.
Among parasitic plants commonly a distinction is made between holoparasites (lacking chlorophyll and photosynthesis, absorbing organic matter from the hosts) and hemiparasites (green, photosynthesising, absorbing mainly inorganic nutrients from the hosts). The borders are, however, not entirely clear, and several representatives of holoparasitic groups have been demonstrated to contain at least traces of chlorophyll.
According to an especially preferred embodiment of the invention, the plant parasite is a hemi-parasite. Examples of hemiparasites useful according to the present invention include, but are not limited to those belonging to the genera listed in Example 2.
Holo-parasites: a list of genera with primarily holo-parasites is disclosed in Example 3 of the present application.
Establishing a plant parasite: By the term establishing a plant parasite on a host plant is normally meant at least the process of germination of a seed or seeds on the host plant. The term establishing may also include the infection of the host plant by the plant parasite and the subsequent emerging of the plant parasite from the host.
For most plant parasites, seed germination is the natural way of plant development. Most plant parasites cultivate the superterrestrial parts of the host plant, e.g. the branches, but some cultivate the sub-terraneous parts of the host plant, e.g. the roots.
For mistletoes, the establishment on the host plant can be divided into two distinct phases. During the first phase, the embryo axis elongates and the mistletoe develops a holdfast, which secures the mistletoe to the host plant. The first phase is non-parasitic.
During the next phase, the parasitic phase, the mistletoe cultivates the interior of the host plant by forming a complex haustorial or endophytic system consisting of haustoria and cortical strands. At a certain point during the parasitic phase, the parasite emerges from the interior of the host plant. The emergence may take place in a place different from the place of sowing, since the mistletoe may have grown a distance of several cm, such as up to 10-15 cm within the plant before it emerges.
Rooting a cut branch. The term refers to the process of rooting cuttings, which is well known to the skilled practitioner within the field of production of pot plants and ornamental plants.
Desired placement of the parasite on the cutting refers to the art of designing a finished plant product with the desired placement of the parasite. When making plants for ornamental purposes (pot plants and ornamentals) it is normally desired that the parasite is clearly visible. This may be done by taking into consideration the height above ground, distance from the shoot apex, the presence of shoots. When making plants for parasite-biomass production due regard must be taken to the later harvesting process. The height above ground is normally the decisive factor.